Hi. Adding some findings to help anyone else with this issue which is work arround that works for me.

Install Ajenti

Configure Nginx to accept .html file = \.(php|html)$

Configure php5-fpm to accept .html file = security.limit_extensions = .php .html

Check all is working.

Install Ajenti-v and the configuration is passed over to the V install.

Activate Nginx in websites.

Cheers :-)

Just to add a note to the problem above relates to Ajenti V.

I have sucessfully managed to run php code in a .html file by installing php-fpm Nginx and not running them under Ajenti V.